1. Field of the Invention
The present invention relates generally to an improved data processing system and in particular, to a computer implemented method, data processing system, and computer usable program code for data transfer between hosts on a partitioned system. Still more, the present invention relates to a computer implemented method, data processing system, and computer usable program code for migration of persistent disk cache from one host to another in a partitioned system.
2. Description of the Related Art
Increasingly large symmetric multi-processor data processing systems, such as IBM eServer™ P690, available from International Business Machines Corporation, DHP9000 Superdome Enterprise Server, available from Hewlett-Packard Company, and the Sunfire 15K server, available from Sun Microsystems, Inc. are not being used as single large data processing systems. Instead, these types of data processing systems are being partitioned and used as smaller systems. These systems are also referred to as logical partitioned (LPAR) data processing systems. A logical partitioned functionality within a data processing system allows multiple copies of a single operating system or multiple heterogeneous operating systems to be simultaneously run on a single data processing system platform. A partition, within which an operating system image runs, is assigned a non-overlapping subset of the platforms resources. These platform allocatable resources include a set of one or more architecturally distinct processors with their interrupt management area, regions of system memory, and input/output (I/O) adapter bus slots. The partition's resources are represented by the platform's firmware to the operating system image.
Each distinct operation system or image of an operating system running within a platform is protected from each other such that software errors on one logical partition cannot affect the correct operations of any of the other partitions. This protection is provided by allocating a disjointed set of platform resources to be directly managed by each operating system image and by providing mechanisms for insuring that the various images cannot control any resources that have not been allocated to that image. Furthermore, software errors in the control of an operating system's allocated resources are prevented from affecting the resources of any other image. Thus, each image of the operating system or each different operating system directly controls a distinct set of allocatable resources within the platform.
With respect to hardware resources in a logical partitioned data processing system, these resources are often disjointly shared among various partitions. These resources may include, for example, input/output (I/O) adapters, memory DIMMs, non-volatile random access memory (NVRAM), and hard disk drives. Each partition within an LPAR data processing system may be booted and shut down over and over without having to power-cycle the entire data processing system.
Failover is the capability to switch over automatically to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active server, system, or network. Failover usually happens without human intervention and generally without warning, unlike switchover.
Systems designers usually provide failover capability in servers, systems or networks requiring continuous availability and a high degree of reliability. In some cases, computer system failover is not desired to be automatic, but is required to allow human intervention to affect the failover. This is called “automated with manual approval”, as the activity is automatic once approval is given. Current failover systems do not provide efficient mechanism to move data from one system to another system.